/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.cayte.create2dcode.qrcode.encoder;

import java.io.UnsupportedEncodingException;
import java.util.Hashtable;
import java.util.Vector;

import com.cayte.create2dcode.common.BitArray;
import com.cayte.create2dcode.common.CharacterSetECI;
import com.cayte.create2dcode.common.ECI;
import com.cayte.create2dcode.common.EncodeHintType;
import com.cayte.create2dcode.common.GF256;
import com.cayte.create2dcode.common.ReedSolomonEncoder;
import com.cayte.create2dcode.common.WriterException;
import com.cayte.create2dcode.qrcode.decoder.ErrorCorrectionLevel;
import com.cayte.create2dcode.qrcode.decoder.Mode;
import com.cayte.create2dcode.qrcode.decoder.Version;

/**
 * @author satorux@google.com (Satoru Takabayashi) - creator
 * @author dswitkin@google.com (Daniel Switkin) - ported from C++
 */
public final class Encoder {

	// The original table is defined in the table 5 of JISX0510:2004 (p.19).
	private static final int[] ALPHANUMERIC_TABLE = { -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x00-0x0f
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x10-0x1f
			36, -1, -1, -1, 37, 38, -1, -1, -1, -1, 39, 40, -1, 41, 42, 43, // 0x20-0x2f
			0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 44, -1, -1, -1, -1, -1, // 0x30-0x3f
			-1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 0x40-0x4f
			25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, -1, -1, -1, -1, -1, // 0x50-0x5f
	};

	static final String DEFAULT_BYTE_MODE_ENCODING = "ISO-8859-1";

	private Encoder() {
	}

	// The mask penalty calculation is complicated. See Table 21 of
	// JISX0510:2004 (p.45) for details.
	// Basically it applies four rules and summate all penalties.
	private static int calculateMaskPenalty(ByteMatrix matrix) {
		int penalty = 0;
		penalty += MaskUtil.applyMaskPenaltyRule1(matrix);
		penalty += MaskUtil.applyMaskPenaltyRule2(matrix);
		penalty += MaskUtil.applyMaskPenaltyRule3(matrix);
		penalty += MaskUtil.applyMaskPenaltyRule4(matrix);
		return penalty;
	}

	/**
	 * Encode "bytes" with the error correction level "ecLevel". The encoding
	 * mode will be chosen internally by chooseMode(). On success, store the
	 * result in "qrCode".
	 * 
	 * We recommend you to use QRCode.EC_LEVEL_L (the lowest level) for
	 * "getECLevel" since our primary use is to show QR code on desktop screens.
	 * We don't need very strong error correction for this purpose.
	 * 
	 * Note that there is no way to encode bytes in MODE_KANJI. We might want to
	 * add EncodeWithMode() with which clients can specify the encoding mode.
	 * For now, we don't need the functionality.
	 */
	public static void encode(String content, ErrorCorrectionLevel ecLevel,
			QRCode qrCode) throws WriterException {
		encode(content, ecLevel, null, qrCode);
	}

	public static void encode(String content, ErrorCorrectionLevel ecLevel,
			Hashtable hints, QRCode qrCode) throws WriterException {

		String encoding = hints == null ? null : (String) hints
				.get(EncodeHintType.CHARACTER_SET);
		if (encoding == null) {
			encoding = DEFAULT_BYTE_MODE_ENCODING;
		}

		// Step 1: Choose the mode (encoding).
		Mode mode = chooseMode(content, encoding);

		// Step 2: Append "bytes" into "dataBits" in appropriate encoding.
		BitArray dataBits = new BitArray();
		appendBytes(content, mode, dataBits, encoding);
		// Step 3: Initialize QR code that can contain "dataBits".
		int numInputBytes = dataBits.getSizeInBytes();
		initQRCode(numInputBytes, ecLevel, mode, qrCode);

		// Step 4: Build another bit vector that contains header and data.
		BitArray headerAndDataBits = new BitArray();

		// Step 4.5: Append ECI message if applicable
		if (mode == Mode.BYTE && !DEFAULT_BYTE_MODE_ENCODING.equals(encoding)) {
			CharacterSetECI eci = CharacterSetECI
					.getCharacterSetECIByName(encoding);
			if (eci != null) {
				appendECI(eci, headerAndDataBits);
			}
		}

		appendModeInfo(mode, headerAndDataBits);

		int numLetters = mode.equals(Mode.BYTE) ? dataBits.getSizeInBytes()
				: content.length();
		appendLengthInfo(numLetters, qrCode.getVersion(), mode,
				headerAndDataBits);
		headerAndDataBits.appendBitArray(dataBits);

		// Step 5: Terminate the bits properly.
		terminateBits(qrCode.getNumDataBytes(), headerAndDataBits);

		// Step 6: Interleave data bits with error correction code.
		BitArray finalBits = new BitArray();
		interleaveWithECBytes(headerAndDataBits, qrCode.getNumTotalBytes(),
				qrCode.getNumDataBytes(), qrCode.getNumRSBlocks(), finalBits);

		// Step 7: Choose the mask pattern and set to "qrCode".
		ByteMatrix matrix = new ByteMatrix(qrCode.getMatrixWidth(),
				qrCode.getMatrixWidth());
		qrCode.setMaskPattern(chooseMaskPattern(finalBits, qrCode.getECLevel(),
				qrCode.getVersion(), matrix));

		// Step 8. Build the matrix and set it to "qrCode".
		MatrixUtil.buildMatrix(finalBits, qrCode.getECLevel(),
				qrCode.getVersion(), qrCode.getMaskPattern(), matrix);
		qrCode.setMatrix(matrix);
		// Step 9. Make sure we have a valid QR Code.
		if (!qrCode.isValid()) {
			throw new WriterException("Invalid QR code: " + qrCode.toString());
		}
	}

	/**
	 * @return the code point of the table used in alphanumeric mode or -1 if
	 *         there is no corresponding code in the table.
	 */
	static int getAlphanumericCode(int code) {
		if (code < ALPHANUMERIC_TABLE.length) {
			return ALPHANUMERIC_TABLE[code];
		}
		return -1;
	}

	public static Mode chooseMode(String content) {
		return chooseMode(content, null);
	}

	/**
	 * Choose the best mode by examining the content. Note that 'encoding' is
	 * used as a hint; if it is Shift_JIS, and the input is only double-byte
	 * Kanji, then we return {@link Mode#KANJI}.
	 */
	public static Mode chooseMode(String content, String encoding) {
		if ("Shift_JIS".equals(encoding)) {
			// Choose Kanji mode if all input are double-byte characters
			return isOnlyDoubleByteKanji(content) ? Mode.KANJI : Mode.BYTE;
		}
		boolean hasNumeric = false;
		boolean hasAlphanumeric = false;
		for (int i = 0; i < content.length(); ++i) {
			char c = content.charAt(i);
			if (c >= '0' && c <= '9') {
				hasNumeric = true;
			} else if (getAlphanumericCode(c) != -1) {
				hasAlphanumeric = true;
			} else {
				return Mode.BYTE;
			}
		}
		if (hasAlphanumeric) {
			return Mode.ALPHANUMERIC;
		} else if (hasNumeric) {
			return Mode.NUMERIC;
		}
		return Mode.BYTE;
	}

	private static boolean isOnlyDoubleByteKanji(String content) {
		byte[] bytes;
		try {
			bytes = content.getBytes("Shift_JIS");
		} catch (UnsupportedEncodingException uee) {
			return false;
		}
		int length = bytes.length;
		if (length % 2 != 0) {
			return false;
		}
		for (int i = 0; i < length; i += 2) {
			int byte1 = bytes[i] & 0xFF;
			if ((byte1 < 0x81 || byte1 > 0x9F)
					&& (byte1 < 0xE0 || byte1 > 0xEB)) {
				return false;
			}
		}
		return true;
	}

	private static int chooseMaskPattern(BitArray bits,
			ErrorCorrectionLevel ecLevel, int version, ByteMatrix matrix)
			throws WriterException {

		int minPenalty = Integer.MAX_VALUE; // Lower penalty is better.
		int bestMaskPattern = -1;
		// We try all mask patterns to choose the best one.
		for (int maskPattern = 0; maskPattern < QRCode.NUM_MASK_PATTERNS; maskPattern++) {
			MatrixUtil.buildMatrix(bits, ecLevel, version, maskPattern, matrix);
			int penalty = calculateMaskPenalty(matrix);
			if (penalty < minPenalty) {
				minPenalty = penalty;
				bestMaskPattern = maskPattern;
			}
		}
		return bestMaskPattern;
	}

	/**
	 * Initialize "qrCode" according to "numInputBytes", "ecLevel", and "mode".
	 * On success, modify "qrCode".
	 */
	private static void initQRCode(int numInputBytes,
			ErrorCorrectionLevel ecLevel, Mode mode, QRCode qrCode)
			throws WriterException {
		qrCode.setECLevel(ecLevel);
		qrCode.setMode(mode);

		// In the following comments, we use numbers of Version 7-H.
		for (int versionNum = 1; versionNum <= 40; versionNum++) {
			Version version = Version.getVersionForNumber(versionNum);
			// numBytes = 196
			int numBytes = version.getTotalCodewords();
			// getNumECBytes = 130
			Version.ECBlocks ecBlocks = version.getECBlocksForLevel(ecLevel);
			int numEcBytes = ecBlocks.getTotalECCodewords();
			// getNumRSBlocks = 5
			int numRSBlocks = ecBlocks.getNumBlocks();
			// getNumDataBytes = 196 - 130 = 66
			int numDataBytes = numBytes - numEcBytes;
			// We want to choose the smallest version which can contain data of
			// "numInputBytes" + some
			// extra bits for the header (mode info and length info). The header
			// can be three bytes
			// (precisely 4 + 16 bits) at most. Hence we do +3 here.
			if (numDataBytes >= numInputBytes + 3) {
				// Yay, we found the proper rs block info!
				qrCode.setVersion(versionNum);
				qrCode.setNumTotalBytes(numBytes);
				qrCode.setNumDataBytes(numDataBytes);
				qrCode.setNumRSBlocks(numRSBlocks);
				// getNumECBytes = 196 - 66 = 130
				qrCode.setNumECBytes(numEcBytes);
				// matrix width = 21 + 6 * 4 = 45
				qrCode.setMatrixWidth(version.getDimensionForVersion());
				return;
			}
		}
		throw new WriterException(
				"Cannot find proper rs block info (input data too big?)");
	}

	/**
	 * Terminate bits as described in 8.4.8 and 8.4.9 of JISX0510:2004 (p.24).
	 */
	static void terminateBits(int numDataBytes, BitArray bits)
			throws WriterException {
		int capacity = numDataBytes << 3;
		if (bits.getSize() > capacity) {
			throw new WriterException("data bits cannot fit in the QR Code"
					+ bits.getSize() + " > " + capacity);
		}
		for (int i = 0; i < 4 && bits.getSize() < capacity; ++i) {
			bits.appendBit(false);
		}
		// Append termination bits. See 8.4.8 of JISX0510:2004 (p.24) for
		// details.
		// If the last byte isn't 8-bit aligned, we'll add padding bits.
		int numBitsInLastByte = bits.getSize() & 0x07;
		if (numBitsInLastByte > 0) {
			for (int i = numBitsInLastByte; i < 8; i++) {
				bits.appendBit(false);
			}
		}
		// If we have more space, we'll fill the space with padding patterns
		// defined in 8.4.9 (p.24).
		int numPaddingBytes = numDataBytes - bits.getSizeInBytes();
		for (int i = 0; i < numPaddingBytes; ++i) {
			bits.appendBits(((i & 0x01) == 0) ? 0xEC : 0x11, 8);
		}
		if (bits.getSize() != capacity) {
			throw new WriterException("Bits size does not equal capacity");
		}
	}

	/**
	 * Get number of data bytes and number of error correction bytes for block
	 * id "blockID". Store the result in "numDataBytesInBlock", and
	 * "numECBytesInBlock". See table 12 in 8.5.1 of JISX0510:2004 (p.30)
	 */
	static void getNumDataBytesAndNumECBytesForBlockID(int numTotalBytes,
			int numDataBytes, int numRSBlocks, int blockID,
			int[] numDataBytesInBlock, int[] numECBytesInBlock)
			throws WriterException {
		if (blockID >= numRSBlocks) {
			throw new WriterException("Block ID too large");
		}
		// numRsBlocksInGroup2 = 196 % 5 = 1
		int numRsBlocksInGroup2 = numTotalBytes % numRSBlocks;
		// numRsBlocksInGroup1 = 5 - 1 = 4
		int numRsBlocksInGroup1 = numRSBlocks - numRsBlocksInGroup2;
		// numTotalBytesInGroup1 = 196 / 5 = 39
		int numTotalBytesInGroup1 = numTotalBytes / numRSBlocks;
		// numTotalBytesInGroup2 = 39 + 1 = 40
		int numTotalBytesInGroup2 = numTotalBytesInGroup1 + 1;
		// numDataBytesInGroup1 = 66 / 5 = 13
		int numDataBytesInGroup1 = numDataBytes / numRSBlocks;
		// numDataBytesInGroup2 = 13 + 1 = 14
		int numDataBytesInGroup2 = numDataBytesInGroup1 + 1;
		// numEcBytesInGroup1 = 39 - 13 = 26
		int numEcBytesInGroup1 = numTotalBytesInGroup1 - numDataBytesInGroup1;
		// numEcBytesInGroup2 = 40 - 14 = 26
		int numEcBytesInGroup2 = numTotalBytesInGroup2 - numDataBytesInGroup2;
		// Sanity checks.
		// 26 = 26
		if (numEcBytesInGroup1 != numEcBytesInGroup2) {
			throw new WriterException("EC bytes mismatch");
		}
		// 5 = 4 + 1.
		if (numRSBlocks != numRsBlocksInGroup1 + numRsBlocksInGroup2) {
			throw new WriterException("RS blocks mismatch");
		}
		// 196 = (13 + 26) * 4 + (14 + 26) * 1
		if (numTotalBytes != ((numDataBytesInGroup1 + numEcBytesInGroup1) * numRsBlocksInGroup1)
				+ ((numDataBytesInGroup2 + numEcBytesInGroup2) * numRsBlocksInGroup2)) {
			throw new WriterException("Total bytes mismatch");
		}

		if (blockID < numRsBlocksInGroup1) {
			numDataBytesInBlock[0] = numDataBytesInGroup1;
			numECBytesInBlock[0] = numEcBytesInGroup1;
		} else {
			numDataBytesInBlock[0] = numDataBytesInGroup2;
			numECBytesInBlock[0] = numEcBytesInGroup2;
		}
	}

	/**
	 * Interleave "bits" with corresponding error correction bytes. On success,
	 * store the result in "result". The interleave rule is complicated. See 8.6
	 * of JISX0510:2004 (p.37) for details.
	 */
	static void interleaveWithECBytes(BitArray bits, int numTotalBytes,
			int numDataBytes, int numRSBlocks, BitArray result)
			throws WriterException {

		// "bits" must have "getNumDataBytes" bytes of data.
		if (bits.getSizeInBytes() != numDataBytes) {
			throw new WriterException(
					"Number of bits and data bytes does not match");
		}

		// Step 1. Divide data bytes into blocks and generate error correction
		// bytes for them. We'll
		// store the divided data bytes blocks and error correction bytes blocks
		// into "blocks".
		int dataBytesOffset = 0;
		int maxNumDataBytes = 0;
		int maxNumEcBytes = 0;

		// Since, we know the number of reedsolmon blocks, we can initialize the
		// vector with the number.
		Vector blocks = new Vector(numRSBlocks);

		for (int i = 0; i < numRSBlocks; ++i) {
			int[] numDataBytesInBlock = new int[1];
			int[] numEcBytesInBlock = new int[1];
			getNumDataBytesAndNumECBytesForBlockID(numTotalBytes, numDataBytes,
					numRSBlocks, i, numDataBytesInBlock, numEcBytesInBlock);

			int size = numDataBytesInBlock[0];
			byte[] dataBytes = new byte[size];
			bits.toBytes(8 * dataBytesOffset, dataBytes, 0, size);
			byte[] ecBytes = generateECBytes(dataBytes, numEcBytesInBlock[0]);
			blocks.addElement(new BlockPair(dataBytes, ecBytes));

			maxNumDataBytes = Math.max(maxNumDataBytes, size);
			maxNumEcBytes = Math.max(maxNumEcBytes, ecBytes.length);
			dataBytesOffset += numDataBytesInBlock[0];
		}
		if (numDataBytes != dataBytesOffset) {
			throw new WriterException("Data bytes does not match offset");
		}

		// First, place data blocks.
		for (int i = 0; i < maxNumDataBytes; ++i) {
			for (int j = 0; j < blocks.size(); ++j) {
				byte[] dataBytes = ((BlockPair) blocks.elementAt(j))
						.getDataBytes();
				if (i < dataBytes.length) {
					result.appendBits(dataBytes[i], 8);
				}
			}
		}
		// Then, place error correction blocks.
		for (int i = 0; i < maxNumEcBytes; ++i) {
			for (int j = 0; j < blocks.size(); ++j) {
				byte[] ecBytes = ((BlockPair) blocks.elementAt(j))
						.getErrorCorrectionBytes();
				if (i < ecBytes.length) {
					result.appendBits(ecBytes[i], 8);
				}
			}
		}
		if (numTotalBytes != result.getSizeInBytes()) { // Should be same.
			throw new WriterException("Interleaving error: " + numTotalBytes
					+ " and " + result.getSizeInBytes() + " differ.");
		}
	}

	static byte[] generateECBytes(byte[] dataBytes, int numEcBytesInBlock) {
		int numDataBytes = dataBytes.length;
		int[] toEncode = new int[numDataBytes + numEcBytesInBlock];
		for (int i = 0; i < numDataBytes; i++) {
			toEncode[i] = dataBytes[i] & 0xFF;
		}
		new ReedSolomonEncoder(GF256.QR_CODE_FIELD).encode(toEncode,
				numEcBytesInBlock);

		byte[] ecBytes = new byte[numEcBytesInBlock];
		for (int i = 0; i < numEcBytesInBlock; i++) {
			ecBytes[i] = (byte) toEncode[numDataBytes + i];
		}
		return ecBytes;
	}

	/**
	 * Append mode info. On success, store the result in "bits".
	 */
	static void appendModeInfo(Mode mode, BitArray bits) {
		bits.appendBits(mode.getBits(), 4);
	}

	/**
	 * Append length info. On success, store the result in "bits".
	 */
	static void appendLengthInfo(int numLetters, int version, Mode mode,
			BitArray bits) throws WriterException {
		int numBits = mode.getCharacterCountBits(Version
				.getVersionForNumber(version));
		if (numLetters > ((1 << numBits) - 1)) {
			throw new WriterException(numLetters + "is bigger than"
					+ ((1 << numBits) - 1));
		}
		bits.appendBits(numLetters, numBits);
	}

	/**
	 * Append "bytes" in "mode" mode (encoding) into "bits". On success, store
	 * the result in "bits".
	 */
	static void appendBytes(String content, Mode mode, BitArray bits,
			String encoding) throws WriterException {
		if (mode.equals(Mode.NUMERIC)) {
			appendNumericBytes(content, bits);
		} else if (mode.equals(Mode.ALPHANUMERIC)) {
			appendAlphanumericBytes(content, bits);
		} else if (mode.equals(Mode.BYTE)) {
			append8BitBytes(content, bits, encoding);
		} else if (mode.equals(Mode.KANJI)) {
			appendKanjiBytes(content, bits);
		} else {
			throw new WriterException("Invalid mode: " + mode);
		}
	}

	static void appendNumericBytes(String content, BitArray bits) {
		int length = content.length();
		int i = 0;
		while (i < length) {
			int num1 = content.charAt(i) - '0';
			if (i + 2 < length) {
				// Encode three numeric letters in ten bits.
				int num2 = content.charAt(i + 1) - '0';
				int num3 = content.charAt(i + 2) - '0';
				bits.appendBits(num1 * 100 + num2 * 10 + num3, 10);
				i += 3;
			} else if (i + 1 < length) {
				// Encode two numeric letters in seven bits.
				int num2 = content.charAt(i + 1) - '0';
				bits.appendBits(num1 * 10 + num2, 7);
				i += 2;
			} else {
				// Encode one numeric letter in four bits.
				bits.appendBits(num1, 4);
				i++;
			}
		}
	}

	static void appendAlphanumericBytes(String content, BitArray bits)
			throws WriterException {
		int length = content.length();
		int i = 0;
		while (i < length) {
			int code1 = getAlphanumericCode(content.charAt(i));
			if (code1 == -1) {
				throw new WriterException();
			}
			if (i + 1 < length) {
				int code2 = getAlphanumericCode(content.charAt(i + 1));
				if (code2 == -1) {
					throw new WriterException();
				}
				// Encode two alphanumeric letters in 11 bits.
				bits.appendBits(code1 * 45 + code2, 11);
				i += 2;
			} else {
				// Encode one alphanumeric letter in six bits.
				bits.appendBits(code1, 6);
				i++;
			}
		}
	}

	static void append8BitBytes(String content, BitArray bits, String encoding)
			throws WriterException {
		byte[] bytes;
		try {
			bytes = content.getBytes(encoding);
		} catch (UnsupportedEncodingException uee) {
			throw new WriterException(uee.toString());
		}
		for (int i = 0; i < bytes.length; ++i) {
			bits.appendBits(bytes[i], 8);
		}
	}

	static void appendKanjiBytes(String content, BitArray bits)
			throws WriterException {
		byte[] bytes;
		try {
			bytes = content.getBytes("Shift_JIS");
		} catch (UnsupportedEncodingException uee) {
			throw new WriterException(uee.toString());
		}
		int length = bytes.length;
		for (int i = 0; i < length; i += 2) {
			int byte1 = bytes[i] & 0xFF;
			int byte2 = bytes[i + 1] & 0xFF;
			int code = (byte1 << 8) | byte2;
			int subtracted = -1;
			if (code >= 0x8140 && code <= 0x9ffc) {
				subtracted = code - 0x8140;
			} else if (code >= 0xe040 && code <= 0xebbf) {
				subtracted = code - 0xc140;
			}
			if (subtracted == -1) {
				throw new WriterException("Invalid byte sequence");
			}
			int encoded = ((subtracted >> 8) * 0xc0) + (subtracted & 0xff);
			bits.appendBits(encoded, 13);
		}
	}

	private static void appendECI(ECI eci, BitArray bits) {
		bits.appendBits(Mode.ECI.getBits(), 4);
		// This is correct for values up to 127, which is all we need now.
		bits.appendBits(eci.getValue(), 8);
	}

}
